Navigational position finding apparatus



Jan. 5, 1960 H. GABLER NAVIGATIONAL POSITION FINDING APPARATUS Filed Dec. 28, 1955 2 Sheets-Sheet 1 win,

Q 0 O O O 0 0 0 4 0 0 INVENTOR. l/E/NZ GAB! 5 Jan. 5, 1960 H. GABLER 2,920,321 NAVIGATIONAL POSITION FINDING APPARATUS Filed Dec. 28, 1955 2 Sheets-Sheet 2 0 f 0,5 see l iocps lzmymeans B\\ a '53 20cps IN V EN TOR. HE/NZ GA 8 1. E9

2,920,321 NAVIGATIONAL POSITION FINDING APPARATUS jHeinzGahler, Hamburg-Vollrsdorf, Germany,

Maximilian Waeehtler, .stein, Germany assignor to Sierksdorf/Post Haifkrug/Hol- Application December 28, 1955, Serial No. 555,980 Claims. (Cl. 343-402) This invention concerns finding apparatus.

In known apparatus hither radio navigational position to used for the determination of the bearing minimumrotatingloop and goniometer direction findersradio bearings of transmitters with identical or almost identical only one after the other.

frequencies could be taken On simultaneous incidence of several signals from different azimuths, interfering voltages would arise in the patterns of the loop aerials receiver due to the figure-8 and would prevent the separate observation of the bearing minima.

The facility for displaying several signals simultaneouslyona cathode ray tube, however, would make it possible .to obtain a correct indicati on of several signals simultaneously incident from different directions and having 'identical or almost identical frequencies, if the respective transmitters could be keyed intermittently. At arapid intermittent keying of, for

example three transmitters,

the eye of an observer would see a stationary indication of three luminous lines corresponding with the direction pf-thethree transmitters.

terrestrial objects.

These lines could'then be used -for a double-angle measurement tion finding of a ship inthe same measurement by means of a for the purpose of posiway as thedouble-angle sextant towards three According to thepresent invention there are provided,

in radio-navigational apparatus transmitters each provided with signals adapted to be displayed on wherein a plurality of a keying device radiate a cathode ray tube,

means associated with each keying device for causing said device to produce a keying "from'the intervals produced interval of different length by the remaining keying devices, and means for synchronously driving said keying devices.

"There is provided an arrangement for direction finding without the aid of a compass, which employs a visual direction finder according and transmitters which are another in their keying and ment thereis attained anv ind from one another througha to .the two-channel principle fully independent from one which operate on the same or approximately .the -same frequencies.

In the arrangeependence of the transmitters selection of switchingintervals of the three-transmitters, the intervals consisting-of a one third mark period and the difierent transmitters.

The driving means for the a two thirds space period for keying devices may comprise synchronous motors which are preferably fed from frequency regulated alternating-current sources of identical nominal frequency,

clockwork means.

local synchronisation devices being effected, if necessary,

of the keying by high precision According to a further feature of the invention, where there are n transmitters in use, the mark to space ratio of the keying intervals is advan tageously made pos t on). a t a o t h w d Peder along which the ship is being steered.

knowing the eourseoflthesl ip,

"2,920,321 Ce .iie en ed, .la 5, 1950 and the keying devicesare ,so operated as to produce ;a number of keying intervals suflieiently high to render the lines displayed on the cathode raytube visually permanent. The principle of the invention .will now be explained for three transmitters Wh Ch are positioned in different azimuths.

The difference between vtheindivid11,z;1l keying device required for the three transmitters and driven by means of synchronous motors from ,three separate alternating current mains of ,50 ,c./,s .,,is,.that ;the keying intervals which y m0 1,.. n isting o .%.m P o and /3 space period, must ,be ,of difierentjlengths for the different transmitters. ,Thus itis effected that, during the operationof the three transmitters, aperiodic displacement of the mark peliodsand space p riods, is obtained, in h a W y h tin .a c rtain.intevvalif nexampl 1 s ond each transmitter is keyed aloneior several times or 'together with the second or with the thirdtransmitter orsimultaneously together withnthe second.andthird transmitter, or that there are prure'breaks in keying.

In the accompanying ,drawing,

Fig. 1 is a diagrammatic view of thedireetion finder;

Fig. 2 illustrates diagrammatically the disposition Qf stations with three transmitters; V

Fig. 3 is-a transmission diagram of a, group of mutually connected transmitters; I

Fig. 4 is another such-diagram and and 2 represent the cross-piecesof a crosswframe in which cross-piece l is installed in amidshipsdirectionand crosspiece 2 across the ship. The frequencies delivered by both cross-pieces are increased in strength by amplifiers 3 and 4 and areled to deflection jplate pairs 5 and 6 of a cathode ray tube. jIhedirectionofthestriking transmitter S which is at an ,angle to the forward, part-of t e s p, then app ar a a "luminous diametrically .disposed line-9 on the screen 8 ofthe cathoderay tube ;7. This line forms the same angle (which can be readon the o e t i scal with e renceto anind ca point the r nsm tt rs ithf 'spee h pil iinstalling such d v on a.sh pli ii telsonecess ry, inmdertd e al t the directionfinding Q1 a.sh pf lchatt .to n wth u s a e d p se n be j nd p de t of as Wel e ro a ompass, if three directions are indicated simultaneously and the angle between these directions is directly determined. This method of location finding without the aid of a compass is employed in terrestrial navigation, in which the angle between the three objects may be ascertained by means of a sextant.

A method of location different azimuths. It jspos sible to finding without the aid of a compass by means of three transmitters is shown schematically in Fig. 2. In figure, characters S S and S indicate the three transmitters and P P and P their corresponding direction indications on the cathode ray lines, it is necessary that transmitters S S and S transrmtone after another in such a quick sequence, that each individual direct-ion will appear as a persisting line.

are indicated by intersecting linesand In order to assure the necessary transmitter operation, these must be linked with one another by wire or by wireless linking means to, thereby assure the necessary time interv-alsvfor the separate, transmission sequences. A diagram of such a group of transmitters is shown in Fig. 3. In thisfigm'e, the transmitting mark periods the space periods are unshaded. Since the ascertaining of position without the use of acompass by the employment of transmitter groups which are dependent on one another through cable or. wireless connectionsis technically very dnficult and requires very great technical effort, this method has not .found universal application until the present. In particular, it cannot be employed whenindividual trans- Qmitters of a transmitter group are installed on ships.

According to the present invention, a transmitter arrangementfor' individual transmitters is disclosed, by which a simultaneous indication from, e.g.,'three directions is possible, wherein, however the indiw'dual transmitters are fully independently keyedfrom one another. The realization of the measure according to the invention for lkeying the transmitters is shownv in an example, wherein three transmitters are employed; 7

Fig. 4 illustrates transmitters for a time oil second. For the first trans mitter 16 keying intervals per second are chosen, for the second 18 and for the third 20. As each keyinginterval consists of /6 mark period'and. space period, there results the illustrated distribution of transmittin'gftimes. All undisturbedv transmitting times (each transmitter alone) are shown as crossed ,lines. Between both there are also breaks in keying, when no transmitter is keyed at all.- The efliciency obtained by the intermittent keying, i.e. undisturbed transmitting times, is 50% example. According to the number of transmitters which :are to be keyed intermittently, the most favourable distribution of keying intervals, in order to obtain the highest possible efliciency, will naturally be chosen.

In Fig. there is shown diagrammatically an arrangement for the keying of three transmitters. The individual transmitters are keyed through equal contact segments (shown in black) which are arranged on a rotor which in each case extend over a third of the circumference, since each switching'point consists of a one third mark period and a two thirds space period. The space periods ot various lengths for the individual transmitters are obindividual rotors difierentrevolution the keyingspeeds in Fig. 4 have a tained by giving the speeds, for instance ratio of 16:18:20.

I claim: V v

1. In radio-navigational position finding apparatus wherein a plurality of transmitters each provided with a keying device radiate signalsladapted to be displayed on a cathode ray tube, means associated with each keying device for causing said device to produce a keying interval of different length from the intervals produced by the remaining keying devices, said means being arranged in a manner to make said transmitters independent from one another, means for synchronouslydriving said keying devices, and a single cathode-ray tube for the display of said signals.

the keying characteristics of the three '2. In radio-navigational position finding apparatus wherein a plurality of transmitters each provided with a device for causing said terval of different length from the intervals produced by 1 device to produce a keying mthe remaining keying devices, said means being arranged in a manner to make said transmitters independent from one another, synchronous motor means for driving each keying device, said motor means fluency-regulated, alternating current nominal frequency,

being fed from fremains of identical and a single cathode-ray tube for the display of said signals. v v

3. In a radio-navigational position finding apparatus wherein a plurality of transmitters each provided with a keying device radiate signals adapted to be displayed on a cathode ray tube, mear'is'associated with each keying device for causing said device to produce a keying interval of different length from the remaining keying devices,

the intervals produced by said means being arranged in a manner to make said transmitters independent from one another, precision clockwork means sationof said keying devices, tube for the display of said signals.

means for driving said keying devices, high for effecting local synchroniand a single cathode-ray 4. In radio-navigational position finding apparatus wherein n transmitters each provided with a keying device radiate signals adapted to be displayed on a cathode ray tube, means associated causing said device to produce with each keying device for a keying interval of dififerent length from the intervals produced by the remaining keying devices, said means being arranged in a manner to make said transmitters independent from one another, said means dividing said keying interval in a mark to space ratio of means for synchronously and a single cathode ray tube signals.

5. In ra driving said keying devices, for the display of said wherein a plurality of transmitters each provided with a keying device radiate signals on a cathode ray tube, ing device for causing said adapted to be displayed means associated with each keydevice to produce a keying interval of difierent length from the intervals produced by the remaining keying devices, said means being arranged in a manner to out from one another,

make said transmitters independmeans for synchronously driving said keying devices so as to produce a number of keying intervals sufficiently high the cathode ray tube visually cathode-ray tube for to render the lines displayed on permanent, and a single the display of said signals.

References Cited in the file of this patent UNITED STATES PATENTS finding apparatus 

